arm: pxa: use common timer functions

arm: pxa: use common timer functions

This patch moves pxa to the common timer functions added in commit

  8dfafdd - Introduce common timer functions <Rob Herring>

The (removed) pxa timer code (specifically __udelay()) could deadlock at
the 32-bit boundary of get_ticks().  get_ticks() returned a 32-bit value
cast up to a 64-bit value.  If get_ticks() + tmo in __udelay() crossed
the 32-bit boundary, the while condition became unconditionally true and
locked the processor.  Rather than patch the specific pxa issues, simply
move everything over to the common code.

Signed-off-by: Andrew Ruder <andrew.ruder@elecsyscorp.com>
Cc: Marek Vasut <marex@denx.de>
Cc: Tom Rini <trini@konsuiko.com>